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Re: Redboot for MBX


--- Gary Thomas <gary@chez-thomas.org> wrote:

> I am confused about why you can run RAM code (eCos
> applications or
> RedBoot), but not ROM code.  Both methods
> [re]initialize the CPU,
> including the MMU, from scratch.  Thus if it fails
> with one, it
> should fail with the other.

I puzzled also.  Any suggestions that would help me
narrow it down? It seems somewhat strange to me: I can
single step through setting the MSR bits to enable
translation, and when I single step the 'sync' command
that follows, I end up at the second instruction in
cyg_hal_default_exceptions with the machine check.
Here are some selected registers before the 'sync' and
where it ends up afterwards:

pc   fe0021c4  fe0021e8
ssr0 fe0021c4  fe0021e8
ssr1 00003032  00001000
lr   fe0021b4  fe0021e4
dar  00000001  ffffff1c
msr  00003032  00001000

> I assume that you're running from the 8bit ROM
> (which is what the
> image on the website is for).  Have you tried
> building an 8bit image
> from scratch?  Or was it just the 32 bit version?

The pre-build rom (dated May 7, 2001) works in my
8-bit flash. Both the 8-bit and 32-bit images that I
build fail.

My short term goal was build a 32-bit image, so I
could remove the 8-bit part (which is necessary to
access hardware plugged into the P1 connector on the
board.) I say "was" because I discovered today that
the "broken" 32-bit rom I built will initialize the
board enough so that I can run my application to
access the hardware.

My longer term goal (~ 3 weeks!) is to be able to
build Redboot for some custom hardware that will be
arriving soon, so I need to get my Redboot builds
working. I'm using the viper hal instead of the mbx
for my starting point, but there are not that many
differences in the code.


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